DE 4432272 C2 describes a method for operating a refrigerating apparatus for air conditioning vehicles. The vapour compression circuit has at least in each case one compressor, one gas cooler, one throttling means and one evaporator. The refrigerating capacity is regulated by a compressor which controls the refrigerant mass flow. The refrigeration efficiency is a function of high pressure in the case of supercritical heat output at the gas cooler. The desired high pressure is set by means of an expansion valve.
EP 0 424 474 B1 describes a method for transcritical and supercritical operation of a vapour compression circuit. The air-conditioning circuit has a compressor, a cooler, throttling means and an evaporator. The refrigeration efficiency is a function of high pressure in the case of supercritical heat output at the cooler. The high pressure is regulated by variation of the refrigerant quantity on the high-pressure side of the circuit.
With this type of operation of a vehicle air conditioner, it is disadvantageous that upon starting up the vehicle air conditioner, the refrigerant mass flow and the high pressure do not immediately rise to the desired value. This is to be ascribed, for example, to the fact that additional pressure drops are produced in the system, and the refrigerant mass distribution in the overall system does riot correspond to the desired distribution. It is particularly disadvantageous when determining the optimum high pressure to use the refrigerant temperature at the gas cooler outlet, since this is itself a function of the high pressure, and thus subjected to incessant fluctuations.
The object of the invention is to improve a vehicle air conditioner so as to permit efficient starting up of the conditioner and efficient and reliable operation of the conditioner.